Electric switch including housing and contact retaining means



May 18, 1965 w. DENNISO 3,134,574 ELECTRIC swI INCLUD H SING AND v CONTACT RETAINI MEANS Filed Feb. 26, 1962 3 Sheets-Sheet l ame/Ker WWW Qmmbmv Jiw fi May 18, 1965 w. G. DENNISON I ELECTRIC SWITCH INCLUDING HOUSING AND CONTACT RETAINING MEANS Filed Feb. 26, 1962 5 Sheets-Sheet 2 I i iHl May 18, 1965 w. G. DENNISON ELECTRIC swITcH mcmmme HOUSING AND coumcw RETAINING MEANS 3 Sheets-Sheet 3 Filed Feb. 26, 1962 United States Patent 3,134,574 ELECTREC SWITCH ENCLUDHNG HOUSENG AND CGNTAiIT RETAHNING MEANS William G. Dennison, Miiwanltee, Wis, assignor to Cutler-Hammer, Inc, Milwaukee, Win, a corporation of Delaware Filed Feb. 26, 1962, Ser. No. 175,669 10 Claims. (Cl. 29l l68) This invention relates to electric switches, and more particularly to switches of the pushbutton operated type.

A primary object of the invention is to provide an improved switch capable of reliable operation under conditions of high acceleration or shock.

A more specific object is to provide in a switch of the aforementioned type a bridging contact member which is statically balanced to resist shock and which has contact surfaces in planes at angles of less than 90 degrees to the direction of movement of the bridging contact member.

Another specific object of the invention is to provide improved means to facilitate mounting and securely retaining stationary contacts of a switch in an insulating housing.

Still another specific object is to provide an improved shock resistant pushbutton and integral watertight seal.

Another object is to provide such a switch which is simple and rugged in construction and employs a minimum number of components all of which lend themselves to economical production and assembly.

A further object is to provide such a switch composed of elements which can be assembled in several positions and combinations to vary the electrical characteristics of the switch.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment of electric switch which will now be described, it being understood that the embodiment illustrated is susceptible of various modifications without departing from the scope of the appended claims.

In the drawings:

FIGURE 1 is a side elevation view of a two unit switch assembly incorporating the invention showing the exterior of the switch enclosure;

FIG. 2 is a top plan view of the switch assembly of FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 2 showing said switch in a normal position with one of the two bridging contacts within a single housing in the open position;

FIG. 4 is a sectional view taken on line 44 of FIG. 2 showing said switch in the normal position with the other of the two bridging contacts in the closed position;

FIG. 5 is a sectional view taken on line 55 of FIG. 2 through the center line of one housing showing said switch in the normal position;

FIG. 6 is a view partially in side elevation and partially in cross section taken on line 66 of FIG. 2;

FIG. 7 is a side elevation view of an alternative form of assembly with a single switch housing mounted behind a panel rather than within an enclosure as shown in FIGS. 1 through 5;

FIG. 8 is an end elevation View of the assembly shown in FIG. 7;

FIG. 9 is a top isometric view of the mounting bracket shown in the assembly in FIGS. '7 and 8', and

FIG. 10 is a bottom isometric exploded view of the "ice switch plunger, one movable contact bridge and one contact bridge spring.

The exterior of a two unit watertight switching station is shown in FIGS. 1 and 2. The enclosure of the embodiment illustrated contains two like momentary contact switch units.

The enclosure case 2a and the enclosure cover 2b are made of insulating material. The cover is fastened to the case by means of bolts 4 which pass loosely through the cover 21; and are threaded into metallic inserts (not shown) embedded in the case 2a. A gasket 6 made of suitably elastic and resilient material such as neoprene is placed between the cover and case to provide a watertight seal. In the ends of the case there are provided apertures 8 (FIG. 6) through which the wiring (not shown) passes to the exterior of the enclosure; Threaded metallic inserts 10 (FIG. 6) are embedded within the apertures to accommodate the threaded ends of the wiring conduit (not shown). Upon the four exterior corners of the base of the enclosure case there are molded mounting pads 12 through which pass apertures id to provide means of mounting the switch assembly. Gussets 16 (FIG. 4) are molded integrally with the sides of case 2a to provide rigidity and strength. Pushbuttons 18 are held in place over openings 2% in cover 217 and within the openings in plates 22 by clamping the peripheral gasket portions 1811 (FIG. 5) of pushbuttons 18 between plates 22 and the cover 2b. The pushbutton mounting plates 22 are in turn fastened to the enclosure 21) by bolts 24.

The pushbutton 13 is made of suitably elastic and resilient material such as neoprene or the like and comprises three principal functional portions. The thick center portion 13a shown in FIG. 5 is a substantially cylindrical solid element which serves to transfer through opening 29 to plunger 26 the force applied externally by the operator and is sufiiciently firm to allow full depre sion of the plunger 2.6. The peripheral gasket portion 182) provides a water-tight seal and serves to hold button E8 in place. The thin intermediate flexible portion 18c is of substantially truncated conical shape and serves to position the center portion 18a in axial alinement with the plunger 26. This intermediate portion further provides the flexibility needed for full depression of center portion 18a and plunger 26. When a downward force is applied to pushbutton i8, flexible portion 180 is subjected to a compression force. Because of its conical shape the flexible portion 180 tends to resist this compression force. Consequently considerable force is required to effect the initial flexure of portion 1&0 and this intermediate flexible portion resists to some extent the movement of center portion Under conditions of acceleration or shock, this resistance to movement tends to prevent the unintentional operation of the switch which would occur if the mass of center portion 13a were allowed to freely move relative to the enclosure cover 2:) and against the plunger 2s.

To provide means for mounting the switch housing 30 within the enclosure case 2a, there are furnished threaded metallic inserts 32 (FIG. 5) embedded in the bottom surface of the case. Two of these inserts are necessary for each switch unit included in the enclosure. Insulating spacers 34 serve to hold the housing 33 in its proper position relative to the cover 212 of the enclosure. Mount ing bolts 36 threaded into inseerts 32 hold housing 34) firmly against the spacers 34'.

When assembled, the top half 30a and the bottom half 3% form a housing 30 which encloses a cavity of three principal portions. Centrally located is a substantially cylindrical cavity which houses the center cylindrical portion 41 of plunger 26 and compression spring 38. Diametrically opposed within this cavity are slots 42 (FIG. 5) within which slide lugs 44 (FIG. on plunger 26. On opposite sides of the central cavity and connected thereto, there are formed the two rectangular contact chambers 46 (FIGS. 3 and 4). The top half 39a and the bottom half 30b of housing 30 are fastened together by two tubular metallic rivets 52 (FIG. 5) which pass through axially alined apertures in each half of the housing. The assembled housing is fastened to the enclosure case 2a by two bolts 36 (FIG. 5) which pass through tubular rivets 52 and insulating spacers 34 and are threaded into metallic inserts 32 embedded in the case.

The structure of the actuator or plunger 26 is best illustrated by FIG. 10 in which the plunger 26 is inverted. The central cylindrical portion 41 encloses an axial cylindrical cavity open to the bottom of the plunger to accommodate return spring 33 (FIG. 5). Upon the outer surface of the center portion 41, there are formed the diametrically opposite lugs 44 which by engagement with slots 42 within the housing 30 serve to prevent rotation of plunger 26 and guide the plunger in its vertical movement. Contact carrier arms 54 are formed diametrically oppositely on the surface of the plunger 26 and intermediately between lugs 44. These arms 54 extend transversely from the plunger into the contact chambers 46 within housing 30. Contact carrier windows 58 are formed within arms 54 and serve to hold movable contacts 60 in operating position. The cylindrical extension 28 of plunger 26, as previously described, passes through an aperture to the exterior of housing 36 as shown in FIG. 5.

Each movable bridging contact 60 is formed from a flat strip of metal of good electrical conductivity. In the center of the middle portion 66a (FIG. 10) of contact 60 there is formed a raised circular area 6% which fits within and positions one end of compression spring 62. With reference to FIG. 10, both ends of contact 60 are first bent downwardly at approximately 45 relative to portion 66a to form portions 60c and then bent upwardly at approximately 90 to portions 600 to form end portions 60d which resultingly lie in planes at approximately 45 to the plane of center portion 60a. The dimensions of portions 60c and end portions 60d are so chosen that the mass of bridging contact 60 which lies above the plane of center portion 60a balances the mass which lies below the plane of center portion 60a. The bridging contact 60 is thereby balanced about its longitudinal axis to prevent rotation about its longitudinal axis when it is subjected to shock forces of a transverse direction. The use of contact making surfaces which lie in a plane 45 to the normal direction of movement of the contacts reduces the effect of shock forces axial to the plunger by reducing the gap between movable and stationary contacts to approximately 70 percent of the displacement of the movable contacts in a direction axial to the plunger. The construction of movable bridging contact 60 incorporates, by economical means, the aforementioned beneficial shock resistant qualities of contact surfaces at 45 to normal movement without adversely affecting the balance of the bridging contact 60 about its longitudinal axis.

Each movable bridging contact 60 is assembled within window 58 of plunger 26 with portions 60c and 60d extending out at both ends. Each contact 60 may be assembled with the contact making faces of portion 60d facing either downwardly, as in the normally open configuration shown in FIG. 3 or upwardly as shown in the normally closed arrangement of FIG. 4. Within each contact window 58 there are four spring retainer walls 64 (FIG. 10). Each Wall 64 traverses half the width of the opening and the two walls 64 at one end of window 58 are positioned horizontally oppositely the pair of walls 64 at the other end of window 58. The walls are so positioned to afford, during manufacture, easy insertion into each window 58 a pair of molding cores, one from each end of the window cavity 58. The spring retainer walls 64 serve to restrain the end of spring 62 which is opposite bridging contact 60. In either the normally open or normally closed configuration, contact 60 is biased toward a pair of spring retainer walls 64 by spring 62. The engagement of portion 600 of contact 60 with the wall 64 prevents movement of contact 60 in its longitudinal direction when in the open position (FIG. 3).

Cooperating with each movable bridging contact 60 are two stationary contact members 66. The housing illustrated holds two sets of contacts, each set comprising two stationary contacts 66 and one movable bridging contact 60. FIG. 3 shows one set of contacts assembled in the normally open position. FIG. 4 illustrates the other set of contacts assembled in the normally closed position. The stationary contact tips 66a are welded to the electrically conductive fiat stationary contact members 66. The terminal or connection end of each contact member 66 exterior to the housing is twisted to facilitate wiring. The member 66 passes through slots formed in the opposing edges of the housing halves 30a and 30b and is thereby clamped in position. Interior of the contact chamber 46, contact member 66 is bent so that the surface of contact tip 66a is held at approximately 45 to the direction of movement of contact 60. The inner end of stationary contact member 66 is further bent so that the inner end is offset and at right angles to the portion of member 66 passing through the housing. These inner ends are firmly anchored in place by insertion into recesses or sockets 68 in the contact chamber 46. The recesses 68 in the upper half 30a of the housing are identical with the slots in the lower half 30b, so that contact members 66 may be assembled with their inner ends inserted in either the top half or the bottom half of the housing.

The combination of reversible moving contacts 60 with reversible stationary contact members permits variations in the electrical characteristics of the switch with a minimum of standard parts since either set of contacts in each housing may be assembled in either the normally open position or the normally closed position.

The operation of the illustrated switch will now be described. This description assumes that one set of contacts is normally open and the other set is normally closed. However,'it is felt that the operation of a switch with variations in contact arrangement will be apparent from the description of this one type. The application of an operating force moves the pushbutton 18 downwardly into contact with the cylindrical extension 28 0f plunger 26. Continued depression forces plunger 26 downwardly against the bias of compression spring 38 to move the bridging contacts 60. The normally closed bridging contact 60 shown in FIG. 4 opens when plunger 26 has advanced sufficiently to bring the upper spring retainer walls into contact with the upper surface of this normally closed bridging contact. Continued movement brings the normally open bridging contact (FIG. 3) into engagement with the cooperating pair of stationary contacts. Still further movement of the plunger increases the contact pressure exerted upon this normally open bridging contact by compression spring 62. Discontinuance of the operating force reverses the process since compression spring 38 thereupon returns plunger 26 and movable contacts 60 to their normal positions.

An alternate method of mounting the invention is illustrated in FIGS. 7, 8 and 9 in which the device is shown assembled to a watertight panel 70 rather than in a small enclosure. The panel 70 is preferably illustrated as a thin flat sheet of metal but, of course, may be constructed of a great variety of materials either electrically conductive or insulative. With reference to FIGS. 7 and 8, the upward facing side of the panel may be considered the front, outside or operators side of the panel, while the arenas t.

downward facing side, on which the housing 30 is mounted, is the rear or inside of the panel. The button 18 is fastened to the front of the panel by means of plate 22 and bolts 72 in a manner similar to that in the enclosed version previously described. Bolts 72 extend through panel 70 and are threaded into mounting brackets 74, thereby securing mounting brackets 74 to the rear of panel '76. The switch housing assembly 30 is fastened to brackets 74 by means of bolts 76 which pass through the tubular rivets 52 within the housing as previously described. The switch when mounted on panel 71 operates in the same manner as when mounted in enclosure 2.

I claim:

1. In an electric switch:

(a) an insulating housing comprising two portions, each having a cavity therein and an open end;

(b) at least one pair of stationary contact members, each of said stationary contact members comprising a terminal portion exterior of said housing and a contact portion within said housing;

(c) means within said housing for receiving and retaining the internal ends of said stationary contact memhere;

(0!) means for securing said portions of said housing to one another with said stationary contact members clamped therebetween adjacent their terminal portions whereby said internal ends of said stationary contact members are rigidly held in said retaining means;

(e) an aperture in one of said housing portions;

(f) an actuator comprising a movable contact carrying portion within said housing and an operating portion extending through said aperture exteriorly of said housing;

g) and a movable contact mounted on said contact carrying portion of said actuator for bridging said stationary contact members.

2. The invention defined in claim 1:

(a) wherein said retaining means comprises sockets in one of said housing portions for receiving the internal ends of the respective stationary contact members and for immovably retaining said internal ends of the respective stationary contact members when said housing portions are secured to one another.

3. The invention defined in claim 2:

((1) together with another pair of depressions in the other housing portion for alternatively receiving and retaining said internal ends of the respective stationary contact members to provide for assembly of said switch such that each set of contacts may be assembled alternatively in either the normally open or normally closed position.

4. In an electric switch:

(a) a switch housing comprising two members of electrically insulating material clamped to one another to form a switch enclosure;

(b) a movable contact within said housing;

(c) an actuator extending through an aperture in a wall of the housing for moving said movable contact;

(d) a stationary contact member comprising a connector portion outside said housing, an intermediate portion where said contact member passes through the wall of said housing, a contact portion inside said housing, and an extreme end inside said housing offset with respect to said intermediate portion;

(e) and means for mounting said stationary contact member comprising means on the adjacent edges of said housing members for clamping said intermediate portion of said stationary contact member therebetween, and means within said housing for retaining said oifset extreme end of said contact portion when so clamped whereby said contact portion is fixed relative to said movable contact and said stationary contact member is readily insertable and removable when said housing portions are separated.

5. In an electric switch:

(a) a switch housing comprising two cup-shaped membears of electrically insulating material clamped to one another at their open ends to form a switch enclosure;

(b) an aperture in the upper housing member;

(6) a spring-biased plunger guided for reciprocal movement within said housing and comprising an actuator end extending through said aperture;

(d) a movable bridging contact mounted on said plunger within said housing;

(e) a pair of stationary contact members each having a connector portion at one end, an intermediate portion where said contact passes through the wall of said housing, a contact portion inside said housing, and an extreme end inside said housing ofiset with respect to said intermediate portion;

(f) and means for mounting said stationary contact members comprising slots molded on the abutting edges of said housing portions for gripping the stationary contact members intermediate the connector portions and contact portions thereof, and recesses molded in the interior surface of the housing for retaining said offset extreme ends when said intermediate portions are so clamped whereby said stationary contact members are securely held and are readily removable when the housing portions are separated.

6. T he invention defined in claim 5 (a) wherein each stationary contact member is bent at an angle of substantially forty-five degrees from said intermediate portion forming a contact portion, and said extreme end is further bent to an angle of substantially ninety degrees from said intermediate portion;

(b) and opposite inner walls of said housing are provided with recesses for retaining said extreme ends to afford reversal of said stationary contact members from normally open to normally closed relation to the movable contact.

7. The invention defined in claim 1:

(a) wherein said movable contact comprises an elon gated member having at its ends contact making surfaces, each lying in a plane at an angle between the direction of movement of said movable contact and a plane normal to said direction of movement, and a center portion for mounting said movable contact on said actuator, the mass of the end portions which support and form said contact making surfaces being distributed to be balanced about the longitudinal axis of said center portion of said movable contact to render said movable contact substantially shockproof in respect to shock forces of a transverse direction.

8. The invention defined in claim 4:

(a) wherein said movable contact carrying portion of said actuator is provided with means aliording reveral of said movable contact to provide for alternative assembly of said movable contact in either the normally open or the normally closed position.

9. The invention defined claim 1:

(a) wherein said contact carrying portion of said actuator is provided with contact carrying window, said movable contact is held within said window by a biasing spring, said spring is held within said window by spring retainer walls forming obstructions at the open ends of said window and traversing half or less than half of the width of said window, and the spring retainer walls at opposite ends of said window are positioned at opposite sides of said window.

10. The invention as defined in claim 1, together with:

(a) a sealed enclosure for said switch having an opening therein;

7 (b) means in said enclosure for rigidly securing said switch therewithin so that the operating portion of the switch actuator is positioned adjacent to said opening;

(c) and means of closing said opening comprising a relatively thick central pushbutton portion effective when depressed to operate said switch actuator;

(d) and, encircling said central pushbutton portion, a substantially conical flexible portion sealing said opening and resiliently supporting said central pushbutton portion, said conical portion having its base adjacent the edges of said opening and extending outwardly from said enclosure to its truncated vertex where it is joined to said pushbutton portion.

References Cited by the Examiner UNITED STATES PATENTS 2,758,169 8/56 Weide 200-16 2,769,882 11/56 Vitus 200-168 2,811,617 10/57 Townsend 200-166 2,924,685 2/60 Burch 200-166 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. IN A ELECTRIC SWITCH: (A) AN INSULATING HOUSING COMPRISING TWO PORTIONS, EACH HAVING A CAVITY THEREIN AND AN OPEN END; (B) AT LEAST ONE PAIR OF STATIONARY CONTACT MEMBERS, EACH OF SAID STATIONARY CONTACT MEMBERS COMPRISING A TERMINAL PORTION EXTERIOR OF SAID HOUSING AND A CONTACT PORTION WITHIN SAID HOUSING; (C) MEANS WITHIN SAID HOUSING FOR RECEIVING AND RETAINING THE INTERNAL ENDS OF SAID STATIONARY CONTACT MEMBERS; (D) MEANS FOR SECURING SAID PORTIONS OF SAID HOUSING TO ONE ANOTHER WITH SAID STATIONARY CONTACT MEMBERS CLAMPED THEREBETWEEN ADJACENT THEIR TERMINAL PORTIONS WHEREBY SAID INTERNAL ENDS OF SAID STATIONARY CONTACT MEMBERS ARE RIGIDLY HELD IN SAID RETAINING MEANS; (E) AN APERTURE IN ONE OF SAID HOUSING PORTIONS; (F) AN ACTUATOR COMPRISING A MOVABLE CONTACT CARRYING PORTION WITHIN SAID HOUSING AND AN OPERATNG PORTION EXTENDING THROUGH SAID APERTURE EXTERIORLY OF SAID HOUSING; (G) AND A MOVABLE CONTACT MOUNTED ON SAID CONTACT CARRYING PORTION OF SAID ACTUATOR FOR BRIDGING SAID STATIONARY CONTACT MEMBERS. 